The invention relates to a component with a first layer which consists essentially of a first material, a second layer which consists essentially of a second material, and at least one intermediate layer located between the first layer and the second layer.
A generic component is known from U.S. Pat. No. 5,698,048. In this case, between the two layers there is an intermediate layer which contains a polymer, but not one of the two materials of the layer.
U.S. Pat. No. 5,454,880 discloses a diode in which one layer of a polymer and another layer which contains fullerene lie adjacent to one another. Here the polymer is made such that it acts as a donor while the fullerenes act as acceptors for charge carriers.
The object of the invention is to devise a generic component which has an efficiency as high as possible for sending and/or receiving electromagnetic radiation, especially light.
In particular, a solar cell with efficiency as high as possible will be created by the invention.
This object is achieved as claimed in the invention by making a generic component such that the intermediate layer contains the first material and/or the second material and that in the intermediate layer a least one material is colloidally dissolved and that the substance has a conductivity different from that first material or the second material.
Therefore the invention calls for devising a component which has at least two layers of two materials with different conductivities and at least one intermediate layer between them. The intermediate layer contains at least one of the two materials and a colloidally dissolved substance. Here colloidally dissolved means that the substance consists of particles or forms them by a chemical reaction or agglomeration and that these particles are located in the material. The particles preferably have a size of 1 nm to 1 microns. Preferably the particles are located in the material such that they form a network via which charge carriers can flow, for example in a percolation mechanism. It is advantageous, but not necessary, that the charge carriers can flow in the material. The colloidally dissolved substance has a conductivity which is different both from the conductivity of the first material and also from the conductivity of the second material. Here it is less a matter of the absolute level of conductivity than of the manner in which the charge carriers are transported.
The first feasible embodiment of the component is characterized in that it contains exactly one intermediate layer. The intermediate layer consists for example of a first material and the substance dissolved therein or of a second material and a substance dissolved therein or of a mixture or compound of the first material with the second material and the substance dissolved therein.
Another, likewise advantageous embodiment of the component is characterized in that between the first layer and the second layer there are a first intermediate layer and a second intermediate layer, that the first intermediate layer adjoins the first layer and that the second intermediate layer adjoins the second layer.
The intermediate layers can be distinguished for example by the first intermediate layer containing essentially the first material and the substance colloidally dissolved therein and by the second intermediate layer consisting essentially of the second material and the substance colloidally dissolved therein.
Furthermore, it is advantageous that in the first intermediate layer a first substance is colloidally dissolved and that in the second intermediate layer a second substance is colloidally dissolved.
An increased current yield or radiation yield is achieved by the first and/or the second material being a semiconductor.
It is especially feasible for the first material and/or the second material to be an organic semiconductor.
For use of the component as a solar cell or as a component of a solar cell it is advantageous for the first material and/or the second material to have suitable light absorption.
Feasibly the organic semiconductor contains substituted perylene pigments. In particular, it is feasible for the perylene pigments to be substituted perylene carboxylic acid imides.
A further increase of the efficiency is achieved by the first material having a type of conductivity different than the second material.
It is especially advantageous that the second material contains an organic complex compound, especially an organometallic complex compound. Here it is preferably a phthalocyanin compound. Use of hydrogen phthalocyanin or metal phthalocyanins, especially zinc phthalocyanin, is especially advantageous.
One preferred embodiment of the component as claimed in the invention is characterized by the substance consisting of a semiconductor material.
The concept semiconductor material comprises all substances known from semiconductor technology as semiconductor materials. The concept of semiconductor material here is however not limited to materials which are generally called semiconductors, but rather comprises all materials which in at least one modification of particle size have a band gap between the valency band and the conduction band. For the charge transport of charge carriers of one type to be achieved what matters is simply the energy position and energy level in the substance. Thus, for example, in the removal of electrons simply one position of the conduction band in the substance which corresponds to the position of the conduction band or of the valency band in the material is necessary. Here the position of the valency band in the substance and thus the band gap are not important. In hole conduction it applies accordingly that the valency band of the substance is feasibly located at an energy level which corresponds to the energy level of the valency band or the conduction band of the material. Examples of the semiconductor material are SnO2 and TiO2.
As a result of quantum size effects the conductivity of the particles of the substance can be different from macroscopic conductivity. For the invention electrical conduction is feasible to the extent by which the charge carriers of one type of conductivity can be removed on a controlled basis. An increase of conductivity by a suitable nanostructure by which for example one substance which macroscopically forms a semiconductor acts as a metal in the layer as claimed in the invention is therefore included at the same time. This also applies to macroscopically metallic materials which as small particles become semiconductors.
One preferred embodiment of the component is characterized by the substance consisting of an organic semiconductor material.
In particular it is feasible for the substance to contain a carbon modification, the carbon modification having a band gap, like for example C60, C70 or graphene.
Especially effective charge transport with simultaneous prevention of electrical short circuits is achieved by the substance being present essentially in the form of particles.
The particles are for example individual molecules, especially individual fullerene molecules, or clusters of several molecules.
The particles preferably have a size from 1 nm to 1 micron, an upper particle size of 200 nm being preferred.
A clear increase of charge transport is achieved in that particles have a concentration which is so great that percolation is formed.
A further increase of efficiency in sending and/or receiving electromagnetic radiation can be achieved by spatially varying the concentration of the substance.
This version of the invention therefore calls for devising a component which has an intermediate layer within which the concentration of a colloidally dissolved substance varies spatially.
The intermediate layer is located between the first layer and the second layer, its being possible that these layers are located within a common carrier material. The first and the second layer can differ both little from one another and can also consist of completely different materials.
Preferably the first and the second material differ simply in that they are doped differently.
One feasible embodiment of the component is characterized in that the concentration of the substance varies within the intermediate layer.
It is especially feasible for the component to be made such that there are at least two substances in the intermediate layer.
Furthermore, it is advantageous for one of the substances to have a concentration which varies spatially differently from the concentration of the other substance.
One feasible embodiment of the component is characterized by the first substance having a Fermi level which differs by at least 20 meV from the Fermi level of the second substance.
Furthermore, it is advantageous that the first substance has a different type of conductivity than the other substance.
One feasible embodiment of the component is characterized in that the one substance has a band gap different from the first substance.
Furthermore, it is advantageous that the band gap of the first substance differs from the band gap of the second substance by at least 20 meV.